Sectional cutting or welding electrode

ABSTRACT

An electrode of carbon material, especially for cutting and welding, which has one end provided with a conical plug and has its other end provided with a socket having a complimentary inner conical surface, and in which the outer surface of the plug and at least that one third of the inner conical surface of said socket which comprises the largest diameter of said inner conical surface is provided with a metallic coating.

United States Patent [54] SECTIONAL CUTTING OR WELDING ELECTRODE 4Claims, 2 Drawing Figs.

[52] U.S.Cl 219/145 323k 35/00 [56] References Cited UNITED STATESPATENTS 2,527,294 10/1950 Bailey 13/18 1,512,786 10/1924 Morton 219/1453,131,290 4/1964 Stepath 219/145 3,399,322 8/1968 Ambe 219/145 PrimaryExaminer-J. V. Truhe Assistant Examiner-Lawrence A. RouseAttorney-Walter Becker ABSTRACT: An electrode of carbon material,especially for cutting and welding, which has one end provided with aconical plug and has its other end provided with a socket having acomplimentary inner conical surface, and in which the outer surface ofthe plug and at least that one third of the inner conical surface ofsaid socket which comprises the largest diameter of said inner conicalsurface is provided with a metallic coating.

PATENTEDuuv 16 I9?! 3.621.187

sum 1 or 2 Fig.1

away/01.9.- w/w-o gar M 32/0 19 440/9,- J) I SECTIONAL CUTTING R WELDINGELECTRODE The present invention relates to carbon electrodes forcutting, welding, and cleaning of steel. Electrodes of this type arecustomarily mounted on holders therefor and are manually orautomatically fed toward the workpiece. Electric current is conveyedthrough said holder to said carbon electrode and builds up an arerequired for the cutting and welding operation to be carried out.

In order to prevent the holder from being damaged when the electrode hasburned ofi to a major extent, it is necessary either to discard theresidual electrode or, by means of a plug connection, to plug theresidual electrode into a new electrode or vice versa.

With heretofore known plug connections of welding electrodes asdisclosed e.g. in US. Pat. Nos. 3,030,544 and 3,13 l ,l90, French Pat.No. 1,383,904 and German Auslegeschrift No. 1,270,707, the copper jacketis interrupted at the area of connection so that the entire current flowat said area has to be passed through the carbon material. In view ofthe rather high resistance at the transition area a premature scalingand overheating will occur at said area of connection when the electrodeis being employed, which fact not infrequently results in an accidentaldisengagement of the connection.

Furthermore, with the said known plug connection, the air entrappedbetween the bottom surface of the hollow cone sleeve of said connectionand the end face of the plug or stud will, in view of the developingheat, expand thereby aiding or bringing about an accidentaldisengagement of the said plug connection. While by providing a bore insaid plug, a venting of the entrapped air can be obtained, there existsthe danger that the said venting bore clogs up by a premature meltingofi' of the copper jacket. Moreover, a proper venting of the gases beingformed from between the conical socket and the conical plug is notassured.

It is, therefore, an object of the present invention to provide aconnectable electrode which will overcome the above-mentioned drawbacks.

It is another object of this invention to provide a connectableelectrode having one end designed as conical socket and the other end asconical plug which will make it possible to interconnect two of saidelectrodes in such a way that a safe and reliable connection will beestablished and maintained throughout the life of the respectiveelectrode in operation.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawing, in which:

FIG. I diagrammatically illustrates in view a socket plug electrodeconnection according to the present invention.

FIG. 2 shows on a considerably enlarged scale the two electrode endspartially sectioned.

The electrode according to the invention which has a conical plug at oneend and a conical socket on the other end, is characterized primarily inthat the entire conical stud or plug and at least one-third of thatconical socket section which contains the greatest diameter of saidconical socket is metallized so that a minimum contact resistance willbe assured between said socket and said plug.

According to a further feature of the present invention, the electrodehas its conical plug provided with a groove extending in thelongitudinal direction of said plug for venting the space between theend face of the plug and the bottom of the socket receiving the same andserving as discharge passage for the gases forming between the conicalsurfaces of said plug and socket. The longitudinal groove also bringsabout a certain clamping efiect, especially in view of the increasedcopper deposit at the edges of the groove interrupting the metalliccover of said conical plug surface. The metallic cover for the conicalsurface of said plug and said socket may be selected from any goodconductor such as Cu, Ag, Au, Ni, Rh, Pt.

Referring now to the drawing in detail, the welding and cuttingelectrode 5 illustrated in FIG. 1 comprises the partially used upelectrode 6 which at the connecting area 7 is connected to a newelectrode 8. The electrode 5 is supported by a holder 9 which receiveshigh-voltage current through a cable 10. The arc 11 between theelectrode and the workpiece 13 which is connected to the negative pole12 brings about the burning off or consumption of the electrode.

FIG. 2 illustrates the two electrodes prior to their connection to eachother. As will be seen from FIG. 2, the rear end of the partiallyburned-off electrode 6 comprises a socket 15 with an inner conicalsurface while the front end of the new electrode 8 is provided with aconical stud or plug 20 having its outer surface provided with ametallic layer, for instance, a copper layer.

The conical plug 20 is characterized by its largest diameter d,, itslength l and the conical angle a. According to a preferred embodiment ofthe invention, a is less than percent and l is greater than percent ofthe electrode diameter D. The angle a is preferably selected frombetween I and 3.

Furthermore, according to a preferred embodiment of the invention, theconical stud 20 has a venting groove 21 provided therein which is sodesigned that the depth t is greater than 50 percent of a and the lengthS equals approximately D, while the width of the groove may be withinthe range of from 5 to 20 percent of d The inner conical surface of thesocket 15 of electrode 6 has substantially the same conical angle as theouter surface of the plug 20. The diameter D, is somewhat smaller thand, so that when the electrode 8 is plugged into the electrode 6, theannular surfaces 16 and 22 are spaced from each other by at least 2.5millimeters. The length L is preferably by 5 percent longer than 1.

The socket l5 and the plug 20 are at their end faces 17 and 23 and atthe annular surfaces 16 and 22 rounded off preferably by radii of from0.5 to 2.5 millimeters. In view of the above outlined features of thepresent invention, an intimate and firm frictional connection will bestablished when the electrode sections are plugged into each other,which connection will become even firmer by melting of the copper duringthe heating of the electrode so that an accidental disengagement of theelectrode sections will, for all practical purposes, be impossible.

As will be evident from the above, with the electrode according to thepresent invention the front end of the electrode may selectively beformed either by the plug or by the socket. However, it is preferable toemploy the plug as the front end inasmuch as it makes the ignitioneasier. It will also be evident that new electrodes can be continuouslyfitted into the burned-off electrodes while the electrode iscontinuously advanced. As will furthermore be evident from the above,the electrode according to the present invention makes it possible tocarry out operations of any duration without interruption.

It is, of course, to be understood that the present invention is, by nomeans, limited to the particular showing in the drawing but alsocomprises any modifications within the scope of the appended claims.

What we claim is:

I. An electrode of carbon material exclusively for welding and cuttingoperations, especially for cutting and welding, having one end providedwith a conical plug of carbon material and having its other end providedwith a socket also of carbon material having an inner conical surface,in which the outer surface of said plug and only approximately at leastthat one-third of the inner conical surface of said socket whichcomprises the largest diameter of said inner conical surface of carbonmaterial are covered by a metallic layer, said metallic layer coveredconical surface of said plug of carbon material and said metallic layercovered conical surface of said socket of carbon material being designedcomplementary to each other so that of two identical electrodes eachhaving one end in the form of a plug and the other end in the form of asocket one end of one electrode will fit into another end of the otherelectrode, and means forming a venting groove extending longitudinallyfrom the end of said plug beyond said conical surface of said plugthereby always during welding and cutting operations obviating trappingof gases in said socket.

2. An electrode according to claim 1, in which only the conical plug ofcarbon material is provided with said means forming the venting grooveextending in the longitudinal direction of said plug itself for adistance longer purposely than tapered interfit of said plug and saidsocket simultaneously for positively always venting gases forming duringthe operation of the electrode between said plug and said socket and forenhancing the clamping efiect between said plug and said socket.

3. An electrode according to claim 2, in which in said plug exclusivelythe depth of said groove extends angularly and at least at one end ofsaid groove exceeds 50 percent of the smallest diameter of said plugitself whereas the width of said groove is within the range of from 5 to20 percent of said smallest diameter of said plug, the length of saidgroove measured at the outer periphery of said plug itself at leastslightly more than equaling approximately the diameter of the electrode.

4. An electrode according to claim 3. in which said metallic layer ismade of a metal selected from the group consisting of Cu, Ag, Au, Ni,Rh, Pt.

* l 0' I I

1. An electrode of carbon material exclusively for welding and cuttingoperations, especially for cutting and welding, having one end providedwith a conical plug of carbon material and having its other end providedwith a socket also of carbon material having an inner conical surface,in which the outer surface of said plug and only approximately at leastthat onethird of the inner conical surface of said socket whichcomprises the largest diameter of said inner conical surface of carbonmaterial are covered by a metallic layer, said metallic layer coveredconical surface of said plug of carbon material and said metallic layercovered conical surface of said socket of carbon material being designedcomplementary to each other so that of two identical electrodes eachhaving one end in the form of a plug and the other end in the form of asocket one end of one electrode will fit into another end of the otherelectrode, and means forming a venting groove extending longitudinallyfrom the end of said plug beyond said conical surface of said plugthereby always during welding and cutting operations obviating trappingof gases in said socket.
 2. An electrode according to claim 1, in whichonly the conical plug of carbon material is provided with said meansforming the venting groove extending in the longitudinal direction ofsaid plug itself for a distance longer purposely than tapered interfitof said plug and said socket simultaneously for positively alwaysventing gases forming during the operation of the electrode between saidplug and said socket and for enhancing the clamping effect between saidplug and said socket.
 3. An electrode according to claim 2, in which insaid plug exclusively the depth of said groove extends angularly and atleast at one end of said groove exceeds 50 percent of the smallestdiameter of said plug itself whereas the width of said groove is withinthe range of from 5 to 20 percent of said smallest diameter of saidplug, the length of said groove measured at the outer periphery of saidplug itself at least slightly more than equaling approximately thediameter of the electrode.
 4. An electrode according to claim 3, inwhich said metallic layer is made of a metal selected from the groupconsisting of Cu, Ag, Au, Ni, Rh, Pt.